Add Nofollow to the Author description

add-nofollow-author-description.php

<?php
/**
 * Plugin Name: Add Nofollow to the Author description 
 * Plugin URI:  https://gist.github.com/web-dev-media/29bb5ac8ed8fb3731ecb
 * Description: Add rel="nofollow" to the author description 
 * Version:     1.0
 * Author:      ../web/dev/media <info@web-dev-media.de>
 * Author URI:  http://www.web-dev-media.de
 * License:     GPL2
 */

/**
 * Add rel nofollow to links at the author box
 * 
 * @author  ../web/dev/media
 */
 
function add_nofollow_author_box( $author_meta ) {
         echo str_replace( '<a href=', '<a rel="nofollow" href=', $author_meta );
}
add_filter( 'the_author_description', 'add_nofollow_author_box' );